source: branches/GeneralizedQAP/HeuristicLab.Encodings.IntegerVectorEncoding/3.3/SimilarityCalculators/EuclideanSimilarityCalculator.cs @ 15605

Last change on this file since 15605 was 15605, checked in by abeham, 20 months ago

#1614: merged trunk into branch

File size: 3.7 KB
Line 
1#region License Information
2/* HeuristicLab
3 * Copyright (C) 2002-2018 Heuristic and Evolutionary Algorithms Laboratory (HEAL)
4 *
5 * This file is part of HeuristicLab.
6 *
7 * HeuristicLab is free software: you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation, either version 3 of the License, or
10 * (at your option) any later version.
11 *
12 * HeuristicLab is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with HeuristicLab. If not, see <http://www.gnu.org/licenses/>.
19 */
20#endregion
21
22using System;
23using HeuristicLab.Common;
24using HeuristicLab.Core;
25using HeuristicLab.Optimization.Operators;
26using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
27
28namespace HeuristicLab.Encodings.IntegerVectorEncoding {
29  [Item("Euclidean Similarity Calculator for IntegerVector", "Calculates the solution similarity based on the Euclidean distance and a transformation into (0;1] between two integer vectors.")]
30  [StorableClass]
31  public sealed class EuclideanSimilarityCalculator : SingleObjectiveSolutionSimilarityCalculator {
32    protected override bool IsCommutative {
33      get { return true; }
34    }
35
36    [Storable]
37    private double scaling;
38    /// <summary>
39    /// The higher the scaling, the higher the similarity score for solutions of larger Euclidean distance.
40    /// A value of 1 means no scaling is applied. The function for squashing the numbers into (0;1] is
41    /// 1 / (1 + x / scaling) where x is the Euclidean distance.
42    /// </summary>
43    public double Scaling {
44      get { return scaling; }
45      set { scaling = value; }
46    }
47
48    [StorableConstructor]
49    private EuclideanSimilarityCalculator(bool deserializing) : base(deserializing) { }
50    private EuclideanSimilarityCalculator(EuclideanSimilarityCalculator original, Cloner cloner)
51      : base(original, cloner) {
52      scaling = original.scaling;
53    }
54    public EuclideanSimilarityCalculator() {
55      scaling = 1;
56    }
57
58    public override IDeepCloneable Clone(Cloner cloner) {
59      return new EuclideanSimilarityCalculator(this, cloner);
60    }
61
62    public static double CalculateSimilarity(IntegerVector left, IntegerVector right, double scaling = 1.0) {
63      if (left == null || right == null)
64        throw new ArgumentException("Cannot calculate similarity because one or both of the provided solutions is null.");
65      if (left.Length != right.Length)
66        throw new ArgumentException("Cannot calculate similarity because the provided solutions have different lengths.");
67      if (left.Length == 0)
68        throw new ArgumentException("Cannot calculate similarity because solutions are of length 0.");
69      if (scaling <= 0)
70        throw new ArgumentException("Cannot choose a 0 or negative scaling value.");
71      if (ReferenceEquals(left, right)) return 1.0;
72
73      var distance = 0.0;
74      for (int i = 0; i < left.Length; i++)
75        distance += (left[i] - right[i]) * (left[i] - right[i]);
76      return 1.0 / (1.0 + Math.Sqrt(distance) / scaling);
77
78    }
79
80    public override double CalculateSolutionSimilarity(IScope leftSolution, IScope rightSolution) {
81      var left = leftSolution.Variables[SolutionVariableName].Value as IntegerVector;
82      var right = rightSolution.Variables[SolutionVariableName].Value as IntegerVector;
83
84      return CalculateSimilarity(left, right, Scaling);
85    }
86  }
87}
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